The analytical potential of mass spectrometry will be developed for applications to the constituents of nucleic acids. Directly combined high performance liquid chromatography-mass spectrometry, utilizing the thermospray ionization technique, will be evaluated with model nucleosides and in the analysis of enzymatic hydrolysates of transfer RNA. The utility of fast atom bombardment, a new method for vaporization and ionization of large and polar molecules, will be explored as a method of detection of complex nucleosides in hydrolysates of nucleic acids. Gas chromatography-mass spectrometry with stable isotope dilution will be further developed and applied to the low-level quantitative measurement of methylated bases in DNA. Computer programs will be written for the analysis of photographically recorded high resolution mass spectra, particularly for applications to complex mixtures.